Add change log entry for psa ECC key derivation

Signed-off-by: Przemek Stekiel <przemyslaw.stekiel@mobica.com>
diff --git a/ChangeLog.d/psa_crypto_key_derivation_for_ECC_keys.txt b/ChangeLog.d/psa_crypto_key_derivation_for_ECC_keys.txt
new file mode 100644
index 0000000..393fa8d
--- /dev/null
+++ b/ChangeLog.d/psa_crypto_key_derivation_for_ECC_keys.txt
@@ -0,0 +1,3 @@
+Features
+   * Add support for psa crypto key derivation for elliptic curve
+     keys. Fixes #3260.